Inspiratory muscle training did not improve exercise capacity and lung function in adult patients with Fontan circulation: A randomized controlled trial

Backgrounds Patients with Fontan circulation have no subpulmonary ventricle and a passive pulmonary perfusion. Considerable percentage of the pulmonary blood flow is driven by pressure shift due to respiration. Impairments in respiratory musculature strength are associated with a reduced exercise capacity. This study investigated the effect of a daily six months inspiratory muscle training (IMT) on exercise and lung capacity in adult Fontan patients. Methods After a lung function and cardiopulmonary exercise test (CPET), 42 Fontan patients (50% female; 30.5 ± 8.1 years) were randomized into either an intervention group (IG), or a control group (CG). The IG performed a telephone-supervised, daily IMT of three sets with 10–30 repetitions for six months. Results After six months of IMT, the IG did not improve in any exercise and lung capacity parameter compared to CG. VO2peak (ΔVO2peak: IG: 0.05 [−1.53; 1.33] ml/kg/min vs. CG: −0.50 [−1.20; 0.78] ml/kg/min; p = .784) and FVC (ΔFVC: IG: 0.07 [−0.16; 0.22] l vs. CG:−0.05 [−0.24; 0.18] l; p = .377) remained unchanged, while FEV1 trended to improve (ΔFEV1: IG: 0.05 [−0.07; 0.13] l vs. CG: −0.10 [−0.19; 0.03] l; p = .082). Only oxygen saturation at rest improved significantly (ΔSpO2: IG: 1.50 [−0.25; 3.00] % vs. CG: −0.50 [−1.75; 0.75] %; p = .017). Conclusions A daily six months IMT did not improve exercise and lung capacity and lung volumes in Fontan patients.